What measures can be taken to prevent oxidation of high-voltage circuit breaker contacts?
2025-02-27
High-pressure circuit breakers operate very frequently and are often affected by mechanical and electrical factors, which can lead to refusal to trip. For circuit breakers already in operation, if a fault recurs on the load side of the circuit breaker, refusal to trip will inevitably cause cascading tripping, expanding the scope of accidents and power outages, so it should be eliminated as soon as possible. Measures to reduce contact resistance and prevent contact oxidation include: (1) Using materials with low resistivity and compressive strength to manufacture contacts. (2) Increasing the pressure between the contact surfaces using springs or spring pads. (3) Plating easily oxidizable copper, brass, and bronze contacts with a protective layer of tin, lead-tin alloy, or silver to prevent increased contact resistance due to oxidation. (4) Coating aluminum contacts with a neutral Vaseline oil layer to prevent oxidation. (5) Using welded copper-aluminum transition joints. (6) The structure of the breakable contacts allows for a certain degree of relative sliding between the moving and stationary contacts, which can wipe away the oxide layer during opening and closing (self-cleaning effect), reducing contact resistance. The DHL-100P intelligent loop resistance tester is developed by Dingsheng Electric Power based on the Ministry of Electric Power standard SD301-88 "Regulations for the handover and preventive testing of 500KV AC power equipment" and the new version of "Preventive testing regulations for power equipment", which stipulates that the DC current for measuring the contact resistance of circuit breakers and isolators should not be less than 100A to ensure accurate test results. The loop resistance tester adopts the latest switching power supply technology, which can continuously output large current for a long time, overcoming the shortcomings of instantaneous current of pulse power supply, and can effectively break through the oxide film of switch contacts to obtain good test results.
Reasons and handling methods for high-voltage circuit breaker refusal to trip
2025-02-27
High-pressure circuit breakers operate very frequently and are often affected by mechanical and electrical factors, resulting in frequent refusal to trip. For circuit breakers already in operation, if a fault recurs on the load side of the circuit breaker, a refusal to trip will inevitably cause cascading tripping, expanding the scope of accidents and power outages. Therefore, it should be eliminated as soon as possible. 1. Reasons for Circuit Breaker Refusal to Trip There are usually two reasons for a circuit breaker to refuse to trip: mechanical failure of the operating mechanism and electrical failure of the operating circuit. When a circuit breaker refuses to trip, the duty personnel should first determine whether the tripping circuit is intact based on the light indication. If the red light is not on, it indicates that the tripping circuit is not connected. At this time, check whether the operating fuse is blown or has poor contact, whether the contacts of the universal switching switch and the auxiliary contacts of the circuit breaker have poor contact, whether the coil of the anti-tripping relay is broken, whether the operating circuit is broken, whether the bulb and lamp are intact, etc. If the operating power supply is good, and the tripping core is weak, it indicates that the tripping coil operating voltage is too high, or the operating voltage is too low, the tripping core is stuck or detached, or the tripping coil itself is faulty. If the tripping core top rod transportation is good, and the circuit breaker still refuses to trip, it may be due to mechanism jamming or detachment of the transmission connecting rod pin. 2. Handling Methods for Circuit Breaker Refusal to Trip After identifying the cause of the refusal to trip, the duty personnel should remain calm and adopt different handling schemes according to the different nature of the fault. For example, during normal isolation operation, if the red signal light is not on, after confirming that the lamp is intact, the operating fuse should be quickly replaced and then the isolation operation should be performed. This should be done by two people, one remotely operating the switching switch and the other observing the isolation core movement on site, while paying attention to maintaining a safe distance. If the core movement is weak, it is core jamming; if the isolation core movement is normal, but the circuit breaker cannot be tripped, it indicates mechanical reverse jamming. At this time, the circuit breaker should be interrupted using the on-site mechanical isolation device. For air circuit breakers and SF6 circuit breakers, the air pressure must be normal before the mechanism can be interrupted. When it is necessary to perform isolation under emergency conditions, such as when the relay protection device operates or manual remote tripping fails, and may cause damage to the main equipment, the duty personnel should immediately manually open the upper-level circuit breaker, then go to the faulty circuit breaker and use the mechanical isolation device to interrupt the circuit breaker; if the mechanical isolation device cannot open the circuit breaker, the isolating switches on both sides of the faulty circuit breaker should be quickly disconnected, then the upper-level power supply should be restored, and the cause should be investigated before further processing; if time permits under accident conditions, the duty personnel should quickly run to the faulty circuit breaker and use the mechanical isolation device to open the circuit breaker; if the mechanical isolation device cannot be opened, the operating mode should be immediately switched, or the busbar circuit breaker or the upper-level circuit breaker should be used to open the circuit breaker, then the isolating switch should be used to isolate the faulty circuit breaker and restore the operating mode. Therefore, it is recommended to regularly use the DGK-S high-voltage switch dynamic characteristic tester to test the high-voltage circuit breaker to eliminate faults in a timely manner. The DGK-S high-voltage switch dynamic characteristic tester is a special high-voltage switch dynamic characteristic tester developed and produced by the Dingsheng Electric Research and Development Center to adapt to the dynamic characteristics of various indoor and outdoor low-oil, high-oil switches, vacuum switches, and sulfur hexafluoride switches. The internal processing of the DGK-S high-voltage switch dynamic characteristic tester uses a single-chip microcomputer as the core for sampling, processing, and output. Its main functional features are the use of Chinese prompts and graphic display in a human-computer dialogue mode, which is simple and fast, suitable for all models and voltage levels of SF6 switches, GIS combined electrical appliances, vacuum switches, and oil switches produced domestically and internationally. It meets the test conditions of live testing of bypass busbars in 500KV substations, accurately measuring time, speed, low voltage, and other functional parameters. The DGK-S high-voltage switch dynamic characteristic tester has many advantages such as intelligence, strong anti-interference ability, and high precision, and is widely favored by customers. However, it should be noted that because the circuit breaker itself is limited by the breaking capacity, it is forbidden to open it when any of the following faults occur, to avoid explosion accidents. (1) Oil circuit breaker without oil, severely lacking oil, or oil seriously carbonized. (2) When the insulating rod of a low-oil circuit breaker is broken. (3) When the gas circuit breaker pressure is too low and cannot be maintained. (4) When the hydraulic system of a circuit breaker using a hydraulic mechanism drops to zero. Once the above phenomena occur, the duty personnel should immediately remove the operating fuse of the circuit breaker, so that the circuit breaker cannot be opened remotely, and even if the circuit breaker is faulty, the protection device will not trip it. At the same time, the duty personnel should hang a "Do Not Operate" warning sign on the operating handle and the operating mechanism of the circuit breaker, and then handle it according to the following principles. (1) If a load circuit breaker fault occurs in the plant (factory) power supply, the load should be transferred according to the instructions of the director or dispatcher, then the busbar connected to the faulty circuit breaker should be de-energized, the circuit breaker should be opened, and then the operation of the upper-level circuit breaker should be restored. (2) If it is indeed a fault of the working power supply circuit breaker of a plant (factory) power supply, the backup power supply circuit breaker should be put into operation, the upper-level circuit breaker of the working power supply should be cut off, and then the faulty circuit breaker should be opened. (3) If a circuit breaker fault occurs and it is necessary to perform busbar switching, when using a busbar circuit breaker or bypass circuit breaker as a substitute, the relay protection specialist should be notified to adjust the setting, and then the relevant units should be notified to shut down for maintenance. When patrolling, if the duty personnel find the following abnormal phenomena, they should take decisive measures, first take measures to prevent the circuit breaker from automatically or remotely closing again, and then perform remote operation to quickly open the circuit breaker and de-energize it: (1) The circuit breaker bushing is cracked. (2) The circuit breaker catches fire. (3) A personal accident occurs that requires the circuit breaker to be opened immediately.
Key Technologies of Intelligent High-Voltage Switchgear
2025-02-27
High-voltage switchgear refers to indoor and outdoor AC switching equipment operating in power systems with voltages of 3kV and above and frequencies of 50Hz and below. It is mainly used for the control and protection of power systems (including power plants, substations, transmission and distribution lines, and industrial and mining enterprises), allowing for the switching of power equipment or lines in or out of operation according to grid operational needs, and quickly isolating faulty sections from the grid in case of equipment or line failures. This ensures the normal operation of the fault-free sections of the grid and the safety of equipment and maintenance personnel. Therefore, high-voltage switchgear is crucial transmission and distribution equipment, and its safe and reliable operation is of great significance to the safe and efficient operation of the power system.
Don't confuse a high-voltage switchgear with a transformer.
2025-02-27
“Box-type substation” is the abbreviation of box-type substation, also known as prefabricated substation or prefabricated substation. It is a kind of high-voltage switchgear, distribution transformer and low-voltage distribution device, which is a factory-prefabricated indoor and outdoor compact distribution equipment arranged in a certain wiring scheme, which organically combines the functions of transformer voltage reduction and low-voltage distribution. It is installed in a moisture-proof, rust-proof, dust-proof, rat-proof, fire-proof, theft-proof, heat-insulating, fully enclosed and movable steel structure box, especially suitable for urban grid construction and transformation, and is a new type of substation that has emerged after the earthwork substation. Box-type substations are suitable for mines, factories and enterprises, oil and gas fields and wind power stations. They have replaced the original earthwork substations and distribution stations, becoming a new type of complete set of power distribution equipment. Box-type substations contain "combination" equipment such as high-voltage input and output lines, metering devices, transformers, low-voltage input lines, and low-voltage distribution output lines, which is equivalent to a complete substation. However, box-type substations are usually installed outside buildings, so there are no special requirements for the selection of transformers, and oil-immersed transformers are generally used. So what is a transformer? Dry-type transformer: It is only a type of transformer. Because the heat dissipation of the dry-type transformer winding is carried out by natural air cooling or forced air cooling (using a fan to force air convection), there are no flammable and explosive substances, so it is widely used in places with relatively high requirements, such as basements in buildings. Different from it is the oil-immersed transformer, which uses the convection of transformer oil for heat dissipation, while transformer oil has a combustion hazard in case of accidents or leakage, and generally cannot be directly installed in the above-mentioned places.
2025-02-27
The 19th National Congress of the Communist Party of China included the high-starting-point planning and high-standard construction of the Xiong'an New Area in its report. 2018-2020 was a period of large-scale concentrated construction in the Xiong'an New Area. The "Guiding Outline for the Planning of the Hebei Xiong'an New Area" proposed strengthening regional power supply and constructing a regional ultra-high voltage power grid. This includes upgrading existing substations and building new 500 kV and 220 kV substations. It also involves actively introducing wind and photovoltaic renewable energy as important sources of power supply for the new area. The new area's power supply reliability rate will reach 99.999%. The planning and construction of the Xiong'an New Area will focus on seven key tasks: First, building a green and intelligent new city to create a world-class, green, modern, and intelligent city; second, creating a beautiful ecological environment, constructing an ecological city where blue and green intertwine, is fresh and bright, and integrates water and city; third, developing high-end and high-tech industries, actively attracting and aggregating innovative elements and resources, and cultivating new driving forces; fourth, providing high-quality public services, constructing high-quality public facilities, and creating a new model for urban management; fifth, constructing a fast and efficient transportation network, creating a green transportation system; sixth, promoting institutional and mechanism reforms, giving play to the decisive role of the market in resource allocation and better playing the role of the government, stimulating market vitality; and seventh, expanding all-round opening up to the outside world, creating a new highland for expanding opening up and a new platform for external cooperation. Therefore, the development of the Xiong'an New Area brings an unprecedented major historical opportunity for enterprises and power grid development. According to media reports, Wang Hongzhi, former director of the Development Planning Department of the State Grid Corporation, previously introduced that the high-level positioning of the Xiong'an New Area puts forward five requirements for the power grid's support: First, to ensure reliable power supply for high-end and high-tech industries, it is necessary to accelerate the construction of ultra-high voltage power grids, build a strong main grid framework, strengthen the distribution network construction, and improve power supply capacity and quality; second, to build a green and intelligent new city, it is necessary to widely apply communication and information technology, proactively absorb clean energy and renewable energy, and build a world-class green and intelligent power grid; third, to create a beautiful ecological environment, it is necessary to build a green and low-carbon energy consumption system, increase the proportion of electricity in terminal energy consumption, and improve energy efficiency; fourth, to provide high-quality public services, it is necessary to establish a modern power supply service system, achieving friendly interaction and intimate service between the power grid and users; and fifth, to support the green transportation system, it is necessary to accelerate the construction of supporting power grids for electric vehicles, high-speed railways, and urban rail transit, build a vehicle networking platform, and ensure energy consumption for green transportation. Among them, supplementing and improving the main grid framework construction of the Xiong'an New Area and ensuring the power support for the construction of the Xiong'an New Area are particularly important. Recently, it was learned that the first tender for substation equipment in the Xiong'an New Area in 2019 has begun. The materials tendered are mainly used for the new construction project of the Rongdong (Jucun) 220 kV substation and the Hexi 110 kV substation. The tendered materials mainly involve high-voltage switchgear, transformers, and combination electrical appliances.
2025-02-27
Hitachi ABB Power Grids recently launched its first new 72.5 kV high-voltage hybrid switchgear for offshore wind power generation – the PASS M00 WT (Semi-Air Insulated Switchgear, Modular type for Wind Turbine), enabling inter-turbine collection lines to operate at higher voltage levels and helping to meet the growing global demand for renewable energy. This innovative solution is about to provide technical support for China's first 66 kV offshore wind farm. In the 300 MW Phase I Huadong Yuhuan Offshore Wind Power Project in Zhejiang Province, Hitachi ABB Power Grids will provide 72.5 kV semi-air insulated switchgear to Dongfang Electric Wind Power Co., Ltd., the wind turbine supplier for the project, helping to optimize the energy structure of the Yangtze River Delta region. China is driving the process of its "energy revolution" through cleaner, more efficient, and digital technologies. According to the International Energy Agency's forecast, by 2024, China's renewable energy generation will account for 40% of the global total. The Huadong Yuhuan Phase I offshore wind power project is scheduled for completion at the end of 2021. It is expected to have an annual equivalent full load operating hours of 2593 hours, providing electricity to approximately 240,000 households in Zhejiang Province. It will also reduce CO2 emissions by 584,000 tons, equivalent to the annual carbon emissions of over 12,600 small passenger cars. The newly designed PASS M00 WT is a compact high-voltage hybrid switchgear specifically designed for wind turbine applications. It is easy to install within the wind turbine tower and can withstand vibration and sudden movements in harsh environments, providing maximum safety assurance for wind farm operators. The new switchgear is equipped with a digital electric operating mechanism, a control cabinet with built-in intelligent monitoring and diagnostic functions. Its relay protection system can be smoothly integrated into the substation automation system through the IEC61850 interface. The switchgear also enables proactive management and remote service of the equipment lifecycle through real-time simulation. Markus Heimbach, Global Head of High Voltage Products Business Unit at Hitachi ABB Power Grids, said: "Our new technology will strongly support the grid integration of renewable energy and help reduce the carbon footprint. Hitachi ABB Power Grids is committed to shaping the future of sustainable energy and driving energy transition by building stronger, smarter, and greener grids."
Address: Xiaoyumen Industrial Zone, Ganjiang Town, Yuhuan City, Zhejiang Province